class Solution(object):
    def findMinArrowShots(self, points):
        """
        :type points: List[List[int]]
        :rtype: int
        """
        points.sort()
        l = len(points)
        res = 0
        for i in range(1, l):
            #区间不重叠
            if points[i][0] > points[i-1][1]:
                res += 1
            else:
                points[i][1] = min(points[i-1][1], points[i][1])
        res += 1
        return res
